UN calls for drastic action to stop climate change

Nick Miller, Berlin and Tom Arup

The world must take radical steps to combat climate change, and begin right away – but if it does, the cost of a greener, healthier future will be surprisingly small.

However if the world wishes to avoid ecological catastrophe, it will probably need new technologies that suck carbon dioxide out of the atmosphere and bury it underground.

This is the message of a new major climate change report from the UN's Intergovernmental Panel on Climate Change, released in Berlin on Sunday.

Members of Greenpeace pose with a giant placard in front of the Brandenburg Gate in Berlin on Sunday. Photo: Reuters

The third and final part of the IPCC's fifth assessment concentrates on what we can do to stop runaway global warming – and how much it will cost.

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More than 200 lead authors, including scientists and economists from around the world, assessed 900 'mitigation scenarios' by which carbon emissions are brought under control.

“Large-scale changes in energy systems and, potentially, land use” are required in order to keep global warming to just two degrees higher than the pre-industrial world, the report found.

As a result of the changes the report proposes, the world must give up about 5 per cent of the projected growth in consumption by the year 2100. To put that in perspective, growth over that time is expected to be between 300 and 900 per cent.

Dutch economist Reyer Gerlagh, co-ordinating lead author of one of the report's chapters, said much of the responsibility for change would fall on developing economies.

Growth in emissions was currently tied to economic and population growth, he said. It would take “a drastic change to the system” to break this connection.

“We really need very tough action, way beyond what anyone has in mind (at the moment),” he said. “But if you implement drastic policy effectively it's actually not expensive at all. It's not half as painful as people think.”

However none of the current international agreements on carbon reduction are enough to limit warming to the two degree figure, which was set as a goal by countries through the UN as the limit for avoiding the worst impacts of climate change. Countries will meet at negotiations in Paris next year in the hope of signing a new global treaty to take effect from 2020.

The key is to 'decarbonise' electricity generation, which will have flow-on effects in industry, buildings and transportation, the report said.

It warned that delaying significant mitigation efforts to beyond 2030 would make it much harder to keep temperature change below two degrees.

The first step must be to replace current coal-fired power plants with natural gas plants, though this is a 'bridge' technology that will have to be phased out in the second half of this century.

By 2050, low-carbon electricity generation (from renewables, nuclear or carbon-capture sources) must increase from the current 30 per cent to more than 80 per cent of total power generation.

And by 2100 there must be no use of fossil fuels at all, in order to hit the two-degree target.

The report summary was critical of existing 'cap and trade' systems for carbon emissions, saying their environmental effect has been limited by poor implementation.

Because it will take time to switch to a low-carbon economy, the report foresees the need for 'BECCS' technology – shorthand for 'bio-energy with carbon capture and storage'. BECCS uses trees and crops to extract carbon from the atmosphere, burns them for fuel, then captures the emissions and buries it underground for centuries.

The report admits there is “limited evidence on the potential for large-scale deployment” of this technology, but says many of its future scenarios require it to work in order to avoid further heating the planet.

Some have warned of the risks in relying on such technology, saying it might give governments an excuse to delay taking action.

“Having the prospect of going to negative emissions in the second half of the century carries the danger of policymakers taking a raincheck now," Australian National University economist Dr Frank Jotzo, a lead-author of the report, told Fairfax Media.

Another report author, Oxford University's John Broome, said “policymakers need to be reminded that (climate change) is doing major harm to other people. It is a moral problem.”

Sabine Minninger, from Bread for the World, said a fundamental transformation of the world's energy system made “profound economic sense”.

“The window for effective action is closing – we have to act now,” she said.

Samantha Smith, from WWF International, said the IPCC report showed that “acting on climate change is possible, beneficial and affordable.”

“If we act now, costs will be only a very small fraction of global economies,” she said. “Those who say it's too hard and too expensive are wrong. But it is very urgent – without immediate action, costs will rise and and impacts will too.”

Environment Minister Greg Hunt said Australia would reduce its emissions by five per cent on 2000 levels by 2020, and would consider further action next year in light of other action by major economies and trading partners and the progress of a new global climate agreement.

Greens leader Christine Milne said the IPCC report showed the Abbott government could no longer pretend "business as usual" on emissions was possible, and it should retain or increase the ambition of Australia's climate change laws, including the carbon price and renewable energy target.

Other findings in the IPCC report:

- Nuclear energy could make an increasing contribution to low-carbon energy production, though there were barriers and risks to this approach.

- More high-density urban planning, more high speed rail and support for cities designed around cycling and walking can have a big effect on future carbon emissions.

- There is a lot of potential in switching to low-carbon fuels for vehicles, such as methane, electricity or hydrogen.

- Having regulations such as energy efficiency standards for consumables may have a benefit, but sometimes higher efficiency can lead to greater consumption.

- Countries must get rid of subsidies for fossil fuels (countries including India and Indonesia subsidise fuel purchases).

- Due to political and administrative problems, it seems more effective to target carbon-reduction policies in particular sectors rather than over an entire economy.